Wireless receiving system.



L. DE FOREST & G. LOGWOOD. WIRELESS RECEIVING SYSTEM. APPLICATION mm MAR. 12, 1914.

Patented Feb. 8, 1916.

mkfmw wt? UNITED STATES PATENT OFFICE.

LEE ma FOREST AND CHARLES LOGWOOD, OF NEW YORK, N. Y., ASSIGNORS TQ RADIO TELEPHONE 8n TELEGRAPH C OMPANY, A CORPORATION OF DELAWARE.

WIRELESS RECEIVING SYSTEM.

Specification of Letters Patent.

Patented Feb. 8, 1916.

Application filed March 12, 1914. Serial No. 824,171.

To all whom it may concern:

Be it known that we, LEE DE Fonns'r and CHARLES LoGwooD, citizens of the United States, residing at New York, in the county of Bronx, State of New York, have made a certain new and useful Invention in Wireless Receiving Systems, of which the following is a specification.

This invention relates to'wireless receiving systems.

The object of the invention is to provide a receiving system for wireless communication wherein the sensitiveness of an audion is utilized as a detector of alternating or pulsating electric currents, whether of high or low frequency, and also as a relay or amplifying device for such currents.

A further object of the invention is to provide circuit arrangements whereby the audion detector and amplifier is rendered i selective as to certain impulses which it is desired to detect a? amplify, to the exclusion of other impulsesdifl'ering in frequency or wave form from those which it is desired to receive or amplify.

Other objects of the invention will appear more fully hereinafter.

The invention consists substantially in the circuit arrangement and relation of parts and interdependent action hereinafter more fully set forth, as illustrated in the accompanying drawings and finally pointedput in the appended claims.

Referring to the accompanying drawings,Figure l is a circuit diagram showing one arrangement of circuits adapted to carry out the principles'of my invention Fig. 2 is a similar view showing a plurality of audion grids and plates. Fig. 3 1s a new similar to Fig. 2, showing a transformer associated in the circuits ofthe audion grids and plates. Fig. 4 is a view'showlng similar circuit arrangements in whlch the audion serves as a relay. The same part is designated by the same reference character wherever 1t occurs throughout the several views.

In the drawings, and referring particularly to Fig. l, N designates the antenna of a wireless receiving system, and E the ground or capacity connectlon therefor.

' Associated with the antenna in' any suitable or. any of the well known methods, is the .usual oscillating circuit). An inductive association of the antenna and oscillating circuit is shown as one form capable of ac complishing the desired results. In this coupling, a transformer-is employed, the primary P, of which, is in the antenna circuit, and the secondary S, in the oscillating circuit, a variable condenser C bein con nected across the terminals thereof 1n the usual manner. This condenser serves to tune the secondary receiving circuit to the frequency of the impulses which it is desired to receive in the well understood manner.

The audion bulb U is provided with the usual filament F, conductor plate W, and intermediate conductor G, preferably in the form of a grid, wire or perforated plate. A battery A is included in the circuit of the filament F. Also included in the battery filament circuit is an adjustable resistance or rheostat indieatedat R, by means of which the battery current may be controlled. A second battery B is employed, one terminal of which is connected to the plate W and the other terminal to one "side of the circuit of filament F. The purpose of the B battery is.

to impress the required electro-motive-force between the filament F and the plate W, and,

to this end, one of the terminals of said battery B is made adjustable, as shown.

The terminals of the oscillating circuit are, respectively, in the grid andplate elements of the bulb. The circuit connection of that portion of the oscillating circuit which terminates in the grid, may, if desired, contain a condenser C The circuit of battery B and plate W,

contains a suitable signal indicating device,

such, for instance, as a telephone receiver T. The circuit WlllCh contains the secondary. S

and terminates in the grid G and plate W,

respectively, is of course a circuit in which high frequency oscillations are created. It may sometimes be desired to prevent and insure against these high frequency oscillations entering the circuit of the battery B. To accomplish this we place a choke coil K in the circuit connection of the plate W with the battery B, and between the plate W and the battery B outside of the terminal connection of coil S with the plate W. While the choke coil K may be dispensed with,- we prefer to employ it for the purpose stated.

In Fig.2, we have shown an arrangement employing two grids G G and two plates W1, W in the audion bulb U,-and we 00D- nect one terminal of the circuit of secondary coil with both grids Gr G and the other terminal of said coil S with plate W,. In

- which contains two grids G G,, and two platesW W as in the caseof Fig. 2, but a transformer having the coils .L are em ployed, the coil L being shunted by the variable condenser C and being connected to both audion ids G, G Thsecondary f coil L is inclu ed in the circuit connection of battery B, which also includes the signal indicating device T, and this circuit connection also includes both the audion plates W W The other terminal ofthe battery B is.

connected to one side of the circuit of'filament F. With this arrangement it will be observed that the grids G G are connected in-parallel to each other, and the plates W -W are likewise connected together in parallel. This we have found to be a preferable arrangement as it gives greater conducting surfaces or, so to speak, larger areas of ionic targets, which greatly increases the sensitiveness of the device, particularly when employed for amplifying the received oscilations. If desired and in order to make more critical the action of the device and to increase its sensitiveness, a permanent magnet, preferably of the horseshoe form as indicated at M, may be employed and so placed as to exert its influence upon the ele ments of theaudion bulb,

In-Fi 4 we have shown an arrangement in whic the audion acts to amplify high frequency oscillations as such and without "transforming the same from high to low frequency as is ordinarily the case with 'radio detectors. In this case L L are respectively, the primary and secondary windings of a hi h frequency transformer, and isconstructed without an iron core. In this connection we note that the transformer L, L of Fig. 3 is designed for low or audio frequencies and referably contains an iron core as indicate In the case of Fig. 4, the primary L, is contained in the circuit connection of the battery B to the audion plate W, while the coil L is contained in a circuit D, which serves as an outlet circuit for the transf rmed and amplified high frequency currents. In' this arrangementv the oscillatin circuit which contains, the secondary 0011 S connected between the grid Grand plate W,-as shown. The impressed voltage of battei'y. I} and the current of battery A. are so relativelyadjuste'd,in practice, that h cu w h lme th and an plate elements of the'detector has a tendency to oscillate at a certain definite frequency 'with a given bulb. This frequency depends so relatively adjusted that the grid circuit .is just ready to' be set into oscillation, we

find that said circuit is highly responsive to received. impulses the group frequency of which is. that at which the circuit tends to oscillate, but not sensitive to group frequencies materially differing from the natural period of the grid circuit.

In the circuit arrangement shown in Fig. 1, the audion itself is'selective to the received high frequency oscillations to an extraordinary degree. In this-case the audion is the source of high frequency oscillating currents, the energy of which is controlled by the batteries A and B, and the frequency of ductance in the coil S, and its associated coil -which is determined by the amount of inl P, and by the adjustment of condensers C 5 0,. If the received impulses be from an undamped continuously oscillating source,

beats are set up in the audion .circuit dueto interference between the received impulses. and those generated in the audion circuit, and if these two frequencies are so relatively adjusted as to be sufficiently near each other this beat note can be heard in the signal device or telephone receiver asa high dis-j tinctive and distinguishable note, the pitch of which can be regulated by .varying the capacity of condensers C, and C or the inductance S. Similarly, as the natural rate of} oscillations of the audion and of the oscil lating circuit connected across its cold grid and plate elements, depend to some extent on the voltage of the battery B, and the temperature of the filament F, the pitch of the; beat note referred to can be regulated to a. certain extent by adjusting or varying the voltage of battery B or the current in the circuit of filament F;

In de Forest Patent No. 995,126, granted June 13, 1911, is shown an audion amplifier? or detector energized from alocal source of: high frequency current having a frequencyf higher than the more essential frequencies of the distant and local sources are nearly;

the same, heat notes will be heard in the telephone receiver associated with the au-f dion detector. In the present arrangement;

however, while the action is similar-the au dion itself sets up the continuous 0801118.;

tions. IVhere the received impulses are slowly damped, that is, where they originate from a transmitting station employing for example, a quenched spark apparatus, the audion and circuit arrangement hereinabove set forth becomes highly. selective to said impulses. by adjusting the audion circuits so that there is set up therein a continuous oscillation the frequency of which coincides, or nearly coincides with that of the impulses which it is desired to receive.

In the arrangement shown in Fig. 3 the audion becomes a source of continuous high frequency impulses for the circuit of secondary S, and also a source. of low frequency impulses in the circuit of the telephone receiver. The latter are rendered very weak or eliminated entirel v by the adjustments referred to. of the impressed voltage of the circuit of battery I). and the current of battery A in the filament circuit, until impulses are received having a spark or group frequency coinciding with that of the telephone-audion circuit. In this manner the audion and its associated circuits become doubly selective.

In the arrangement shown in Fig. r, the audion becomes an amplifier for high frequency currents as such. The oscillating circuit is shown connected between the grid and the plate. The amplified current circuit is that circuit which is connected at one terminal to the plate \V and at the other terminal to one side of the filament; The condenser in this arrangement, may, if desired, be dispensed with, and the condenser C, may be merely a blocking condenser of large capacity instead of a small variable condenser.

It is to be observed that in all cases, exce'pt that shown in Fig. 2, the positive side of battery B is connected to the audion plate W, (Figs. land 4) or to the plates IV, \V, (Fig. 3). In Fig. 2, the positive side of battery B is connected to one side of filament F, and the other side of said battery l is connected to plate 7,.

In practice we prefer to 'insert an impedance coil L, in the circuit of battery B, said coil having a resistance of several thousand ohms and containing an iron core, as indlcated 1n the drawing. The amplified high frequency currents are transformed by means of the air core hlgh frequency transformer L L at any desiredratio of volt.-

age, and led off at the secondary terminals I).

While We have shown various circuit arrangements embodying the broad principles of our invention We Wish it to be understood that other arrangements besides those specifically shown and described may be employed for accomplishing the same or similar results Without departing from the spirit and scope of our invention; We do not desire to limit ourselves, therefore, in the broadest scope of our invention to specitic circuit arrangements shown. But

'hat we claim as new and useful and of our own invention, and desire to secure by Letters Patent is,

1. In a wireless apparatus, an audion having a grid element and a wing or plate element. and a series oscillating circuit having one terminal associated with the grid element and the other terminal associated with the wing or plate element.

2. The combination with an audion having a grid and a win; element, of a series oscillating circuit having its terminals respectively connected to said grid and wing elements.

3. In a wireless receiving system, a sensitive detector including cold electrodes and a hot electrode. and a plurality of inductively related circuits associated therewith. one of said circuits being a series circuit and connected at its terminals with said respective cold electrodes.

4. In a wireless receiving system, a detector including cold electrodes and a hot electrode. and a series oscillating circuit connectedat its terminals to said cold electrodes respectively.

5. In a wireless receiving system, a detector including cold electrodes and a hot electrode, and a plurality of inductively re lated circuits associated therewith, one of said circuits being a series oscillating circuit and having its terminals respectively connected to the cold electrodes.

(3. In a wireless receiving system, a sensitive gas detector including cold electrodes and a hot electrode, a plurality of inductively related circuits associated with said electrodes, one of said circuits being a series circuit and having its terminals respectively connected to the cold electrodes, and means trode, a series oscillating, a current supply. and a voltage supply circuit associated therewith, the terminals of the oscillating circuit being respectively connected to the cold elec- -trodes, and means to produce oscillations in said last mentioned circuit.

9. In a Wireless receiving system, an audion having cold electrodes and a hot electrode, a series oscillating, a current and a voltage supply circuit associated with said audio-n, said oscillating circuit having its terminals respectively connected to the cold electrodes, and said voltage supply circuit having one-terminal connected to a cold electrode and the other to the hot electrode.

10. In a wireless receiving system, an audion having coldelectrodes and a hot electrode, a series oscillating, a current supply and a voltage supply circuit associated with said audion, said oscillating circuit having its terminals respectively connected to the cold electrodes, and said voltage supply circuit being inductively related to the oscillating circuit and having one terminal connected to a cold electrode and the other to the hot electrode.

11. In a wireless receiving system, an audion having cold electrodes and a hot electrode, a series oscillating circuit having its terminals respectively connected to the cold electrodes, a current supply circuit connected to the hot electrode, and a voltage supply circuit having one terminal connected to a cold electrode and the other to the hot electrode.

12. In a wireless receivin system, an audion having cold electrodes and a hot electrode, a series oscillating circuit having its terminals respectively connected to the cold electrodes, a current supply circuit con nected to the hot electrode, a voltage supply circait having oneterminal connected to a cold electrode and the other to the hot electrode, and means to vary the voltage in said voltage supply circuit. i

13. In a wireless receiving system, an audion having cold electrodes and a hot electrode, a series oscillating circuit having its terminals respectively connected to the cold electrodes, a current supply circuit connected to the hot electrode, a voltage supplycircuit having one terminal connected toacold electrode and the other to the hot electrode, I

and means to vary the current in the current supply circuit. v

14. In a wireless receiving'system, an audion having cold electrodes and a hot electrode, a series oscillating circuit having its terminals respectively connected to the cold electrodes, a current supply circuit con nected to the hot electrode, a voltage supply circuit having one terminal connected to a cold electrode and the other to the hot electrode, means to vary the voltage and current supplies.

15. In a wireless receiving system, an audion having cold electrodes and a hot electrode, a series oscillating circuit having its terminals respectively connected to the cold electrodes, a. current supply circuit connected to the hot electrode, a voltage supply circuit having one terminal connected to. acold electrode and the otherto the hot electrode, and means to vary the voltage in said voltage supply circuit, said oscillating circuit being inductiveiy related to one of said supply circuits.

16. In a Wireless receiving system, an audion having cold electrodes and a hot electrode, a series oscillating circuit having its terminals respectively connected to the cold electrodes, a current supply circuit connected to the hot electrode, a voltage supply circuit having one terminal connected to a cold electrode and the other to the hot electrode,

and means to vary the voltage in said voltage supply circuit said oscillating circuit being inductively related to said voltage supply circuit.

17. In a wireless receiving system, an audion having cold electrodes and a hot electrode, a series oscillating circuit having its terminals respectively connected to the cold electrodes, :1 current supply circuit connected to the hot electrode, a voltage supply circuit having one terminal connected to a cold electrode and the other to the hot electrode, and means to vary the voltage in said voltage supply circuit and a transformer coupling between the oscillating and one of said supply circuits.

18. In a wireless receiving system, an audion having cold electrodes and a hot electrode, a series oscillating circuit having its terminals respectively connected to the cold electrodes, at current supply circuit connected to the hot electrode, a voltage supply circuit having one terminal connected to a cold electrode and the other to the hot electrode, and means to vary the voltage in said voltage supply circuit and a transformer coupling be tween the oscillating and voltage supply circuits. I

19. In a Wireless receiving system, an audion having a filament, a plurality of grids and a plurality of plates, a current supply circuit connected to the filament, a. voltage supply circuit connected to the plates and an oscillation circuit connected to the grids.

20. In a Wireless receiving system, an audion having a filament, a plurality of grids and a plurality of plates, a current supply circuit connected to the filament, a voltage supply circuit connected to the plates, and an oscillation circuit connected to the grids, said circuits being interlinked with each other.

21. In a wireless receiving system, an auoscillating circuit having its terminals respectively connected to said cold electrodes.

23. In a wireless receiving system, an an.

tenna circuit, a series oscillating circuit associated therewith, an audion having cold electrodes and a hot electrode, said series oscillating circuit having its terminals respectively connected to said cold electrodes, a signal device, a circuit therefor, the terminals of said signal circuit respectively connected to one of the cold electrodes and to the hot electrode, said oscillating circuit having one terminal connected to one of the cold electrodes and the other terminal connected to the other cold electrode and between said last mentioned electrode and the signal device.

In testimony whereof We have hereunto set our hands in scribing Witnesses, on this 7th day of March A. D., 1914. a

' LEE DE FOREST.

CHARLES LOGWOOD.

Witnesses:

ISABEL LEVINSON, V,

JOSEPHINE PERNICE.

the presence of the sub- 15 

